Efficient organic light emitting diodes and photodetectors

Organic electronic devices are now finding commercial applications in displays, with potential use emerging in inexpensive electronic devices currently emerging. We discuss means for obtaining extremely high efficiency organic light emitting devices (OLED) for displays, and organic photodetectors for power conversion and other detection applications, by effectively confining and capturing molecular excited states by appropriate and precision insertion of energy barriers in these devices. The first device is an electrophosphorescent OLED. We show that by employing metallorganic phosphor molecules, nearly 100% internal electroluminescent efficiency can be achieved. Fundamentally, the presence of the heavy metal atom in molecular structure induces efficient intersystem crossing between the singlet and triplet excitonic states. Furthermore, it considerably reduces the time constant for triplet emission to only a few hundred nanoseconds. Using this approach, we have succeeded in demonstrating very high efficiency electrophosphorescent OLED emission in the red, green and blue spectral regions.